Static soft reduction control model based on PLC and Wincc

Abstract

The invention provides a static soft reduction control model based on a PLC and Wincc. The static soft reduction control model comprises a first-stage PLC control system. The primary PLC control system comprises a plurality of PLCs, and each PLC is connected with an encoder, a displacement sensor, a pressure sensor and an electromagnetic valve which are arranged on site; and the network switch is respectively connected with the plurality of PLCs, the second-level system, the third-level system and the industrial personal computer with a human-computer interface. The invention aims to develop a brand-new static soft reduction model by utilizing a primary PLC (Programmable Logic Controller) and Wincc technology, so as to overcome a plurality of problems of the existing dynamic soft reduction technology in practical application, and provide an innovative solution for improving the casting blank quality, improving the production efficiency and reducing the production cost.

Description

Technical Field

[0001] The present invention relates to the technical field of steel continuous casting, and in particular to a static soft reduction control model based on PLC and WinCC. Background Art

[0002] In steel continuous casting production, dynamic soft reduction technology is widely used by domestic and foreign steel companies because it can significantly improve the quality of ingots, effectively optimize the solidification structure, and solve the problems of center segregation and porosity.

[0003] However, with the in-depth application, its technical difficulties have become more prominent. First, the industrial computer and the secondary software control system have poor stability. Compared with the PLC control system, the industrial computer and the software control system have low reliability in complex continuous casting environments and often have abnormalities. Although the manufacturer has optimized them many times, they have not been solved. Second, there are strict requirements on the accuracy of the roll gap. The on-site equipment will cause wear and deformation due to long-term operation. The inherent error causes the roll gap error to be large, and frequent calibration is required, which consumes a lot of manpower, material resources, and time, affecting production efficiency and enterprise operating costs. Third, factors such as steel type, cooling, and crystallizer wear make it difficult to determine the reference roll gap, resulting in large errors in the press-down, which sometimes affects the quality of the ingot. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to propose a static soft pressing control model based on PLC and WinCC to solve the technical problem of poor stability of the existing static soft pressing control method.

[0005] The technical means adopted in the present invention are as follows:

[0006] A static soft-pressing control model based on PLC and WinCC includes a first-level PLC control system; the first-level PLC control system includes several PLC controllers, each of which is connected to an encoder, a displacement sensor, a pressure sensor, and a solenoid valve set up on site; a network switch is respectively connected to the several PLC controllers, the second-level system, the third-level system, and an industrial computer with a human-machine interface.

[0007] Furthermore, the control method of the first-level PLC control system includes reference roll gap collection and light pressure control.

[0008] Furthermore, the method for collecting the reference roll gap specifically includes:

[0009] Each straightening machine is equipped with a dynamic reference roll gap. The actual roll gap at a selected position on the billet under hot billet pressure serves as the reference roll gap of the straightening roll. The reference roll gap is collected automatically and manually. The automatic collection includes automatic collection at the start of casting, automatic collection when changing the tundish, and automatic collection when exiting the soft reduction.

[0010] The automatic data collection method for pouring is as follows: a data collection reference position is selected by setting the billet head length L, wherein the data collection reference position is the position where the billet head coordinates exceed the distance L between the straightening rollers. After pouring, under the pressure of the hot billet, the reference position is used to collect the actual roll gaps as the billet head coordinates pass through each straightening roller in sequence, which is used as the reference roll gap.

[0011] The automatic data collection method for tundish change is as follows: utilizing the special situation that the casting speed returns to zero for a long time during the casting process during tundish change to calculate the coordinates of the casting strand joint line position, and selecting the collection reference position by setting the joint line length D. The collection reference position is the position where the joint line coordinate exceeds the distance D between the straightening rollers. Under the pressure of the hot billet, the actual roll gap is collected as the reference position passes through each straightening roller in sequence as the coordinate increases, which is used as the reference roll gap.

[0012] The automatic data collection method for exiting light pressure is as follows: when exiting light pressure during the production process, the coordinates of the casting billet at the position of the straightening roller at this time are recorded, and the position 0.5 meters after the coordinate is selected as the data collection reference position. Under the pressure of the hot billet, the reference position collects the actual roll gap as it passes through each straightening roller in turn as the coordinate increases, and serves as its reference roll gap.

[0013] Furthermore, the method of light pressure control specifically includes:

[0014] After the continuous casting machine starts casting, the first-level PLC control system automatically collects the reference roll gap. After the reference roll gap is collected, the target roll gap is calculated based on the reference roll gap and the set pressure reduction. After the light pressure reduction is applied, the first straightening roll with a non-zero pressure reduction is set as the initial current roll. The first-level PLC control system automatically reduces the pressure in sequence starting from the initial current roll. The control principle is as follows:

[0015] S1. Determine whether the initial current roller has a valid pressing amount set; if so, execute S2; if not, determine the next rack;

[0016] S2. Determine whether the initial reference roll gap of the current roll has been collected; if so, execute S3; if not, wait until the reference roll gap is collected; calculate the initial target roll gap of the current roll;

[0017] S3, after the billet moves a specified distance, execute S4;

[0018] S4, driving the initial current roller to adjust downward so that the actual roller gap value of the initial current roller reaches the target roller gap value of the initial current roller;

[0019] S5. Determine whether the next roller of the initial current roller has a valid pressing amount set; if so, use the next roller as the new current roller and proceed to S6; if not, the pressing is terminated and the subsequent racks do not press down any more;

[0020] S6. Determine whether the new reference roll gap of the current roll has been collected; if so, execute S7; if not, wait until the reference roll gap is collected and calculate the new target roll gap of the current roll;

[0021] S7, determine whether the initial current roller is pressed down into place, if so, execute S8; if not, wait until it is pressed down into place;

[0022] S8, judging whether the distance traveled by the initial current roll exceeds the new current roll, if so, executing S9; if not, waiting until the distance exceeds the new current roll;

[0023] S9, driving the new current roller to adjust downward so that the actual roller gap value of the new current roller reaches the target roller gap value of the new current roller;

[0024] S10. Repeat S5 to S9 until the straightening rollers of all stands are pressed down.

[0025] Furthermore, in S2, the target roll gap = the reference roll gap - the accumulated pressing amount, and the accumulated pressing amount is the sum of the current roll pressing amount and the previous roll pressing amount.

[0026] Furthermore, in S1, the effective pressing amount is a single roller pressing amount of 0-10 mm, and in S3, the specified distance is 0.5 m.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] Unlike traditional dynamic soft reduction technology, which suffers from the poor stability of industrial and machine-level software control systems, this invention relies on the casting machine's own PLC control system and Wincc host computer software. The PLC control system, renowned for its excellent anti-interference capabilities and high reliability, operates stably in the complex environment of continuous steel casting, effectively avoiding production interruptions caused by system anomalies. The Wincc host computer software offers excellent versatility and flexibility, enabling human-machine interaction functions such as parameter setting, status display, and operator operation. This further enhances the stability of the entire control system, ensuring the continuity and smooth operation of the continuous casting production process.

[0029] In view of the strict requirements on roll gap accuracy in the existing technology, the long-term operation of on-site equipment will cause wear and deformation, resulting in large roll gap errors and the need for frequent calibration. The present invention can better adapt to the inherent errors of the equipment through an optimized static light pressure control model. On the one hand, the PLC control system is used to accurately control the hydraulic cylinder to drive the straightening roller, realizing the closed-loop control of "set pressure → actual pressure → deviation correction", effectively reducing the impact of roll gap errors on the pressure effect; on the other hand, through innovative reference roll gap collection methods, including automatic collection at the start of casting, automatic collection when changing the middle bag, and automatic collection when exiting light pressure, the reference roll gap can be accurately obtained under different working conditions, avoiding problems such as large pressure errors caused by the difficulty in determining the reference roll gap, thereby greatly reducing the frequency requirements for equipment calibration, reducing the investment in manpower, material resources and time, and reducing the operating costs of the enterprise.

[0030] Based on an in-depth analysis of the current status of the continuous casting process, the present invention fully utilizes the characteristics of the continuous casting machine to achieve stable operation at a constant temperature and constant drawing speed under most working conditions, and develops a new static light reduction model. Through precise reduction control, the solidification structure of the ingot can be effectively improved, and quality problems such as center segregation and looseness can be solved. In practical applications, the control model can accurately calculate the target roll gap based on the set reduction amount and the collected reference roll gap, and perform reduction control on each straightening roll in turn to ensure that the ingot is subjected to a uniform and reasonable reduction force during the solidification process, thereby significantly improving the intrinsic quality and surface quality of the ingot, improving the product qualification rate, and bringing higher economic benefits to the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0032] Figure 1 This is a structural diagram of the control system of the present invention.

[0033] Figure 2 This is a schematic diagram of the light pressing control principle of the present invention.

[0034] Figure 3 This is the principle diagram of automatic collection during pouring of the present invention.

[0035] Figure 4 This is the principle diagram of automatic data collection for the middle pack replacement of the present invention.

[0036] Figure 5 This is a schematic diagram of the automatic collection principle of the present invention by lightly pressing down to exit. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0039] The light reduction model proposed in the present invention is a static light reduction control model based on PLC and Wincc. It is a control system implemented by the PLC control system of the casting machine itself and the Wincc host computer software. It mainly utilizes the stability and reliability of the first-level PLC control system and the versatility and flexibility of the host computer Wincc. The core of the control system is mainly completed by the PLC control program, and the human-machine interface such as parameter setting, status display, and worker operation is implemented by Wincc software. The PLC controls the hydraulic cylinder to drive the straightening roller to achieve precise reduction closed-loop control through the electromagnetic reversing valve. A closed-loop control of "set reduction amount → actual reduction amount → deviation correction" is formed. The present invention is designed according to the casting machine design of 5 streams, and each stream is equipped with a Siemens 400 PLC controller for on-site signal acquisition, motion control, logical operation, network communication, etc., which is the control core. Ethernet connections are used between PLCs, between PLCs and host computers, and between other systems, and are implemented by network switches.

[0040] like Figure 1 As shown, the present invention provides a static light pressing control model based on PLC and Wincc, including a first-level PLC control system; the first-level PLC control system includes several PLC controllers, each of which is respectively connected to an encoder, a displacement sensor, a pressure sensor and a solenoid valve set up on site; a network switch is respectively connected to several PLC controllers, a second-level system, a third-level system and an industrial computer with a human-machine interface.

[0041] Secondary system: refers to the dynamic light pressure computer model system (completed by a server), which is used for dynamic light pressure control (the server mainly completes the tracking control of the model and the interface display; the PLC is used to control the field equipment, and the data between them is realized through Ethernet communication).

[0042] Level 3 system: Mainly used for data collection and status display of factory-level process flow, not for control, and only reads and collects data from the PLC system.

[0043] The control method of the first-level PLC control system includes reference roll gap acquisition and light pressure control.

[0044] The method for collecting the reference roll gap specifically includes:

[0045] Each straightening machine is equipped with a dynamic reference roll gap. The actual roll gap at the selected position on the billet under the hot billet pressure is used as the reference roll gap of the straightening roll. The collection of the reference roll gap includes automatic collection and manual collection. The automatic collection includes automatic collection at the start of casting, automatic collection when changing the tundish, and automatic collection when exiting the soft pressure. Figure 3-5 As shown;

[0046] The automatic data collection method for pouring is as follows: a data collection reference position is selected by setting the billet head length L, wherein the data collection reference position is the position where the billet head coordinates exceed the distance L between the straightening rollers. After pouring, under the pressure of the hot billet, the reference position is used to collect the actual roll gaps as the billet head coordinates pass through each straightening roller in sequence, which is used as the reference roll gap.

[0047] The automatic data collection method for tundish change is as follows: utilizing the special situation that the casting speed returns to zero for a long time during the casting process during tundish change to calculate the coordinates of the casting strand joint line position, and selecting the collection reference position by setting the joint line length D. The collection reference position is the position where the joint line coordinate exceeds the distance D between the straightening rollers. Under the pressure of the hot billet, the actual roll gap is collected as the reference position passes through each straightening roller in sequence as the coordinate increases, which is used as the reference roll gap.

[0048] The automatic data collection method for exiting light pressure is as follows: when exiting light pressure during the production process, the coordinates of the casting billet at the position of the straightening roller at this time are recorded, and the position 0.5 meters after the coordinate is selected as the data collection reference position. Under the pressure of the hot billet, the reference position collects the actual roll gap as it passes through each straightening roller in turn as the coordinate increases, and serves as its reference roll gap.

[0049] like Figure 2 As shown, the method of light pressure control specifically includes:

[0050] After the continuous casting machine starts casting, the first-level PLC control system automatically collects the reference roll gap. After the reference roll gap is collected, the target roll gap is calculated based on the reference roll gap and the set pressure reduction. After the light pressure reduction is applied, the first straightening roll with a non-zero pressure reduction is set as the initial current roll. The first-level PLC control system automatically reduces the pressure in sequence starting from the initial current roll. The control principle is as follows:

[0051] S1. Determine whether the initial current roller has been set with a valid reduction amount; if so, execute S2; if not, determine the next stand; generally, the reduction amount of a single roller is limited to 0-10mm (this value can be appropriately modified according to process requirements), that is, if the reduction amount is set to 0, the roller will not be pressed down;

[0052] S2. Determine whether the initial reference roll gap of the current roll has been collected; if so, execute S3; if not, wait until the reference roll gap is collected; calculate the initial target roll gap of the current roll; only after the reference roll gap is collected can the target roll gap be calculated, which is target roll gap - reference roll gap - cumulative reduction (the sum of the reduction of this roll and the previous reduction).

[0053] S3. After the billet moves a prescribed distance, S4 is executed. The prescribed distance in this embodiment is 0.5 m to avoid the base position being damaged and pressed, which would result in inaccurate subsequent base roll gap acquisition.

[0054] S4, driving the initial current roller to adjust downward so that the actual roller gap value of the initial current roller reaches the target roller gap value of the initial current roller, and the error can be less than 0.1mm;

[0055] S5. Determine whether the next roller of the initial current roller has a valid pressing amount set; if so, use the next roller as the new current roller and proceed to S6; if not, the pressing is terminated and the subsequent racks do not press down any more;

[0056] S6. Determine whether the new reference roll gap of the current roll has been collected; if so, execute S7; if not, wait until the reference roll gap is collected and calculate the new target roll gap of the current roll;

[0057] S7, determine whether the initial current roller is pressed into place. If the error is less than 1mm, it is considered to be in place. If so, execute S8; if not, wait until it is pressed into place;

[0058] S8, determine whether the distance traveled by the initial current roller exceeds the new current roller. The center distance between two adjacent straightening rollers is 1.5m. If it is greater than 1.8m, it is considered to exceed. If so, execute S9; if not, wait until it exceeds the new current roller.

[0059] S9, driving the new current roller to adjust downward so that the actual roller gap value of the new current roller reaches the target roller gap value of the new current roller;

[0060] S10. Repeat S5 to S9 until the straightening rollers of all stands are pressed down.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A static soft reduction control model based on PLC and Wincc, characterized in that: It includes a first-level PLC control system; the first-level PLC control system includes several PLC controllers, each of which is connected to an encoder, a displacement sensor, a pressure sensor and a solenoid valve set up on site; the network switch is connected to several PLC controllers, a second-level system, a third-level system and an industrial computer with a human-machine interface.

2. The static soft reduction control model based on PLC and Wincc according to claim 1 is characterized in that: The control method of the first-level PLC control system includes reference roll gap acquisition and light pressure control.

3. The static soft reduction control model based on PLC and Wincc according to claim 2 is characterized in that: The method for collecting the reference roll gap specifically includes: Each straightening machine is equipped with a dynamic reference roll gap. The actual roll gap at a selected position on the billet under hot billet pressure serves as the reference roll gap of the straightening roll. The reference roll gap is collected automatically and manually. The automatic collection includes automatic collection at the start of casting, automatic collection when changing the tundish, and automatic collection when exiting the soft reduction. The automatic data collection method for pouring is as follows: a data collection reference position is selected by setting the billet head length L, wherein the data collection reference position is the position where the billet head coordinates exceed the distance L between the straightening rollers. After pouring, under the pressure of the hot billet, the reference position is used to collect the actual roll gaps as the billet head coordinates pass through each straightening roller in sequence, which is used as the reference roll gap. The automatic data collection method for tundish change is as follows: utilizing the special situation that the casting speed returns to zero for a long time during the casting process during tundish change to calculate the coordinates of the casting strand joint line position, and selecting the collection reference position by setting the joint line length D. The collection reference position is the position where the joint line coordinate exceeds the distance D between the straightening rollers. Under the pressure of the hot billet, the actual roll gap is collected as the reference position passes through each straightening roller in sequence as the coordinate increases, which is used as the reference roll gap. The automatic data collection method for exiting light pressure is as follows: when exiting light pressure during the production process, the coordinates of the casting billet at the position of the straightening roller at this time are recorded, and the position 0.5 meters after the coordinate is selected as the data collection reference position. Under the pressure of the hot billet, the reference position collects the actual roll gap as it passes through each straightening roller in turn as the coordinate increases, and serves as its reference roll gap.

4. The static soft reduction control model based on PLC and Wincc according to claim 1 is characterized in that: The method for soft pressing control specifically includes: After the continuous casting machine starts casting, the first-level PLC control system automatically collects the reference roll gap. After the reference roll gap is collected, the target roll gap is calculated based on the reference roll gap and the set pressure reduction. After the light pressure reduction is applied, the first straightening roll with a non-zero pressure reduction is set as the initial current roll. The first-level PLC control system automatically reduces the pressure in sequence starting from the initial current roll. The control principle is as follows: S1. Determine whether the initial current roller has a valid pressing amount set; if so, execute S2; if not, determine the next rack; S2. Determine whether the initial reference roll gap of the current roll has been collected; if so, execute S3; if not, wait until the reference roll gap is collected; calculate the initial target roll gap of the current roll; S3, after the billet moves a specified distance, execute S4; S4, driving the initial current roller to adjust downward so that the actual roller gap value of the initial current roller reaches the target roller gap value of the initial current roller; S5. Determine whether the next roller of the initial current roller has a valid pressing amount set; if so, use the next roller as the new current roller and proceed to S6; if not, the pressing is terminated and the subsequent racks do not press down any more; S6. Determine whether the new reference roll gap of the current roll has been collected; if so, execute S7; if not, wait until the reference roll gap is collected and calculate the new target roll gap of the current roll; S7, determine whether the initial current roller is pressed down into place, if so, execute S8; if not, wait until it is pressed down into place; S8, judging whether the distance traveled by the initial current roll exceeds the new current roll, if so, executing S9; if not, waiting until the distance exceeds the new current roll; S9, driving the new current roller to adjust downward so that the actual roller gap value of the new current roller reaches the target roller gap value of the new current roller; S10. Repeat S5 to S9 until the straightening rollers of all stands are pressed down.

5. The static soft reduction control model based on PLC and Wincc according to claim 4 is characterized in that: In S2, the target roll gap = the reference roll gap - the accumulated reduction amount, where the accumulated reduction amount is the sum of the current roll reduction amount and the previous roll reduction amount.

6. The static soft reduction control model based on PLC and Wincc according to claim 4 is characterized in that: In S1, the effective pressing amount is a single roller pressing amount of 0-10 mm, and in S3, the specified distance is 0.5 m.

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